Weapons that deliver electrified projectiles have been used for self defense and law enforcement. These weapons typically deliver a stimulus signal through a target where the target is a human being or an animal. One conventional class of such weapons includes conducted energy weapons of the type described in U.S. Pat. Nos. 3,803,463 and 4,253,132 to Cover. These weapons typically fire projectiles toward the target so that electrodes carried by the projectile make contact with the target, completing a circuit that delivers a stimulus signal via tether wires through the electrodes and through the target. Other conventional conducted energy weapons omit the projectiles and deliver a stimulus signal through electrodes placed in contact with the target when the target is in close proximity to the weapon.
The stimulus signal may include a series of relatively high voltage pulses known to cause pain in the target. At the time that the stimulus signal is delivered, a high impedance gap (e.g., air or clothing) may exist between electrodes and the target's conductive tissue. Conventional stimulus signals include a relatively high voltage (e.g., about 50,000 volts) signal to ionize a pathway across such a gap of up to 2 inches. Consequently, the stimulus signal may be conducted through the target's tissue without penetration of the projectile into the tissue.
In some conventional conducted energy weapons, a relatively higher energy waveform has been used. This waveform was developed from studies using anesthetized pigs to measure the muscular response of a mammalian subject to an energy weapon's stimulation. Devices using the higher energy waveform are called Electro-Muscular Disruption (EMD) devices and are of the type generally described in U.S. patent application Ser. No. 10/016,082 to Patrick Smith, filed Dec. 12, 2001, incorporated herein by this reference. An EMD waveform applied to an animal's skeletal muscle typically causes that skeletal muscle to violently contract. The EMD waveform apparently overrides the target's nervous system's muscular control, causing involuntary lockup of the skeletal muscle, and may result in complete immobilization of the target.
Unfortunately, the relatively higher energy EMD waveform is generally produced from a higher power capability energy source. In one implementation, a handheld launch device includes 8 AA size (1.5 volt nominal) batteries, a large capacity capacitor, and transformers to generate a 26-watt EMD output in a tethered projectile.
A two pulse waveform of the type described in U.S. patent application Ser. No. 10/447,447 to Magne Nerheim filed Feb. 11, 2003, provides a relatively high voltage, lower amperage pulse (to form an arc through a gap as discussed above) followed by a relatively low voltage, higher amperage pulse (to stimulate the target). Effects on skeletal muscles may be achieved with 80% less power than used for the EMD waveform discussed above.
There exists a significant need for a more effective stimulus signal for use in conducted energy weapons to immobilize a human target without lasting injury or death. In the decade preceding this application, annually over 30,000 people died of bullet wounds in the United States. Further, thousands of police officers are injured as a result of confrontations with non compliant members of the general public each year. Even larger numbers of these non-compliant subjects are injured in the process of being taken into police custody. Without systems and methods for delivering more effective stimulus signals, further improvements in cost, reliability, range, and effectiveness cannot be realized for conducted energy weapons. Applications for conducted energy weapons will remain limited, hampering law enforcement and failing to provide increased self defense to individuals.